Delegates dev/rc/release build steps to bread-ecosystem's pinned Arch
container via ci/build.sh, pinned to bread-ecosystem commit
147cfbbf96ae4b171027defa1130d2caddb934b1. Adds a check.yml workflow
for fast clippy/test signal on feature/fix branches, matching the
pattern proven in breadpad. No ci/deps.txt needed — breadbar's
dependencies (zbus, resvg, gtk4-layer-shell, hyprland) are all pure
Rust or already covered by the shared image's package set.
